you can give west nile your self or the vet what ever you are comfortable with. the first year you give the shot it needs to be givin twice, the second dose 4 weeks after the first and then a booster every year. if im wrong let me know because i wouldnt want to do this wrong, several west nile cases in my area in the last year and i would never forgive myself if i could have prevented one of my horses from getting it.

If you live in a place where there are mosquitoes all year long you might want to booster them every 6 months. You would have to talk to your vet but up here it has never been an issue cause the bugs are dead for 6 months a year anyways

You are correct on the vaccination schedule.
You want to first vaccinate early spring the 1st one (before the nasty mosquito's) then 3-4 weeks for the second booster, then once a year there after.